Why do ionic compounds have high melting points?
Ionic compounds have high melting points because of the strong electrostatic forces of attraction between the oppositely charged ions in the giant lattice.
GCSE Chemistry
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In more detail
In a giant ionic lattice every positive ion is surrounded by negative ions and vice versa, held together by strong electrostatic forces acting in all directions. A large amount of energy is needed to overcome these many strong forces, so ionic compounds melt (and boil) at high temperatures.
Key points for the exam
- Giant ionic lattice with strong electrostatic forces between oppositely charged ions.
- Lots of energy needed to overcome the forces → high melting point.
- Compounds with higher ionic charges generally have even higher melting points.
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